Add emacspeak tutorial: functions

_emacspeak_tutorials/functions.md

@@ -0,0 +1,12 @@
+---
+title: "Functions in C"
+layout: emacspeak_tutorial
+yt_link: "https://youtu.be/UV-xmgS3qhc"
+zip_link: "/assets/emacspeak-tutorials/functions.zip"
+---
+
+Functions allow us to modularize our programs into many small parts.
+Of course if we need to do something once at the start of our program, and once again at the end,
+it will be rather inconvenient to copy and paste all our code all the time.
+
+Hope everything makes sense. If not, let me know.